Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance

Measurement:

Check resistance of pump at the pump connections with the wires disconnected.
Test for short circuit between the
Live (L) and Neutral (N),
Live (L) and Earth
Neutral (N) and Earth.
Short Circuits on any of these tests would cause a fuse to blow.
Also check for any water leaks on or around the pump.