Motor can be used for both piston engine and for electric motors.
The word engine is normally used only for steam or gas or diesel powered motors, like you have in most cars or trucks.
Engines have tolerances between their parts, but you don't normally speak of a motor having tolerance.
Excessively used doesn't work out well. Choose either run for a long time and worn out (over worked), or run very hard for an (assumed) shorter time period. Worked hard, run hard, overloaded, or overstressed all work here.
A motor run hard will be running under a lot of stress, or heavily loaded, or under a lot of strain.
A motor worked too hard (to the point of damage) will be overstressed, overloaded, or severly strained.