It may or may not be worth rebuilding. Bearings are cheap, as are (usually) the seal for the pump. THe pump bearings may not be inexpensive though. You need to provide more information:
How much was the replacement motor?
Did you have to replace the pump as well?
You could take the pump and motor to a motor repair shop and see how much they will charge you for rebuildioing if it is only the motor that needs repair, and then you would have a spare.
ANyone that is handy with tools can replace bearings and pump seals.