pump motor sizing

I have a 22000g AG round pool. My 1 hp Pump motor is humming until the GFI shuts it off. I disassembled the pump, cleaned, reassembled, reconnected it to the pool system. It ran for about 20 minutes at which time it began to humm and then stopped. When I had the pump apart, the motor looked a little corroded at the barrings at the pump housing. Before I take it to the pool guy to have it lubbed I want to be sure that the motor is the right size. Any calculations to help with that?