It could be the pump--and specifically the motor for the pump. The reason there is no water left in the drum is because there is a bypass for the extraneous water left in the drum at spin cycle. The pump then draws out the additional water. I'd check the pump line and assembly first, using the information found here:
http://www.fixya.com/support/t289401-error_code_20. I had the same problem as you shortly before I started getting the error code 20, and you'll see how I (and others) solved it. I recommend trying the shortcut
Keith_Mann offers and if the white basket has not gotten forced into the central pump chamber as it did with mine.
If there is no clog in the pump or drain line, the problem is likely the actual motor of the pump. I'd recommend troubleshooting it by leaving the back panel off, then taking a towel you've thoroughly wetted down and placing it in the drum and setting your machine to spin. Make sure the washing machine is still turned around so you can see the back assembly. Crouch down and watch to see/hear if the pump motor is activating. If not, you'll have to call a repairman to have it replaced.
Good luck. Hope you can fix it yourself!