Will PG&E give you power usage for the previous owner?
How old is the pump system?
There has to be a tank somewhere or else the pump would cycle on & off very quickly when the water is being used. The rapid cycling would cause the start windings in the motor to fail pretty quickly.
There are numerous reasons why the pump is using so much power, it could be worn out, there could be a split or hole in the pipe, the spline coupler between the pump & motor could be worn and slipping or the screen on the pump intake could be plugged with iron. Any of those conditions will prevent the system from coming up to pressure and shutting the pump off.