I wouldn't alter any factory wiring arrangement at the pump. I agree with Dspark that installing a GFCI receptacle adjacent to the pond is the right thing to do. Makes sense because the cord is only eight feet long. Could the pump sit close to the edge of the pond and then run a longer hose to the fountain? Some of the ponds I've seen have a pump box installed at one end of the pond and a tube, hose, etc., routed to the other end.
