Sears and Roebuck, but I have never heard of Sears Simpson.
No matter, you can change the bearings if the unit looks new enough to be rebuilt. If it's old and nasty looking, a new pump might be in order.
You can not get the motor off by removing the four bolts unless the Pump has a Coupled Shaft. That means a coupling with a set screw to seperate the Impeller from the Motor Shaft. 95% of the Pumps today don't have the Coupled Shaft.