Tesla is taking the food out of my mouth. Actually I was motor winder for a while and Tesla has it. If the pump is so rare and the motor so special that an off the shelf replacement cannot be found then rewind makes sense. Or if the motor is actually expensive enough to ecenomically rewind.
So if you think the pump is nearing the end of life then buy a spare and make sure you have a high water alarm.
As for testing the condition of the motor a partial discharge device or maybe some of the new ultrasonic test equipment if a local engineer has one? PD testers are pricy and rare.
