Rattling grinding noise in left front wheel fwd

It sounds like there might be an issue with the installation of the new wheel bearing, or a related component. Grinding and whining noises are often signs of mechanical issues in the drivetrain, and if the problem only started after the wheel bearing replacement, it's likely related to that.
I would recommend having the vehicle inspected by a qualified mechanic as soon as possible. They should be able to diagnose the issue and determine whether the problem is with the new wheel bearing, or another component in the drivetrain.
In the meantime, I would avoid driving the vehicle as much as possible, especially if the grinding and whining noises persist. Continued driving could cause further damage and make the repair more expensive.

Front wheel drive vehicles have drive axles with CV Joints and they also have sealed bearings.
That translates into "the parts have a limited service life before they have to be replaced".
Considerinig the age of your vehicle I would suggest that the time for some repairs is rapidly approaching.
While these tasks are within the abilities of many "home mechanics", they involve dismantling some complicated components.
If you want to consider trying, I would recommend that you check out this video clip.
https://www.youtube.com/watch?v=SYBs6-k_NO0

There are many things the grinding noise can be. I would start with the breaks though as that sounds like the most likely culprit. If they are grinding, odds are you have ruined your rotors and/or drums. This means that you are looking at about $50-$70 in new parts per wheel (Total of $200 to $280) to replace, assumming only the pads and rotors/drums needs to be replaced.

Please note that breaks can be a good DIY project, but this takes an intermediate skill level with some expereince. Some vehicles are easier than others. Drum style breaks can be especially tricky as they relie on a system of springs that can be challenging to work with. There is also a hydrulic system that can have issues. If you see break fluid when you take off the wheels and drums, you have much larger issues and I would recommend getting in touch with someone more qualified.

It is most likely the drivers side front wheel bearing. These are an easy fix for a mechanic, or if you mechanically inclined you could try it yourself (2 hour max job) and part runs around 50-70 bucks.

MDX runs as FWD most all the time so I would have them check CV joints and boots usually need attention after 100K miles

It sounds more like a possibly bad CV joint in an axle shaft or internal differential problem. There is no mechanical linkage to the front axle, its all electronically controlled. The front suspension is pretty good there aren't a lot of rattle type noises created from it. I need more info to diagnose better. Does it do it only moving? or stopped? over bumps only? in 4wd only? while turning? certain gears or speed only?

when turning left vehicle distributes weight to right front wheel bearing causing load. since u describe a noise in right front while driving straight i would suspect failed right front wheel bearing. see if your noise changes/goes away while turning right that should tell u 4 sure

It sounds like to me front wheel bearing hub assembly.

sounds more like a wheel bearing,jack the car up and support with axle stands,then grab the front left wheel at both sides and shake it hard.then grab it at the top and bottom and shake it hard.if a knocking can be felt through the wheel then its most likely a wheel bearing.repeat the test for the rear wheel.also with the vehicle jacked up,spin the wheel and put your ear next to it,if it makes a dry whirring or grinding sound as it spins,this is a symptom of a worn wheel bearing

I know on older cars that popping noise from the front end is often the cv joint, which is used in front wheel drive vehicles. Get it checked quick. The grinding noise could be a bad brake pad, which also needs to be checked a.s.a.p. Good Luck.