if there is water flowing it is almost a horse a piece. if there is not water moving then let it turn off and stay off.
if there is not water moving the motor will cook in the heat it creates.
if there is water moving it is hard to say. a motor technically only has so many starts in it. this might be 1000, 10000, or 100000000 starts. we just don't know, but we do know that every time a motor starts it weakens the insulation on the winding which in the end will cause motor failure. so, do you want to plan for the pump turning on and off or do you want to just let it run? good question. but it is very important that there is a cooling flow of water past the motor.