Here's the skinny:
You ain't getting that pump off of there because when the old belt wore out, it also overheated the steel motor pulley and the shaft going into the pump. This literally bonds the plastic pump shaft to the steel motor shaft. You will have to order a new pump and chisel the old one off.
My guess is that if this machine was making a growling noise during the spin cycle before you noticed the broken belt, then you have much worse problems than a belt & pump. If this is indeed the case, drop what you are doing and go shopping for a new machine.