The reason for not using electric pump is not overheating.
From A330 FCTM
ELECTRICAL PUMPS
These electrical pumps are not designed to replace the Engine Driven Pump to supply flight
controls, as they are power limited (the hydraulic electric pump flow represents 18 % of an engine driven pump flow) and they cannot cover high transient demand from flight controls. Furthermore,
if they were used in case of dual hydraulic failure, they could degrade the aircraft handling (Flight Control jerk).
As a general rule, do not manually select a HYD ELEC PUMP ON, except temporarily, to retract the spoilers if they remain out after a hydraulic failure.