It seems common practice to put a protection diode upstream of a quickly-switching mosfet, in parallel with an inductor (motor, relay):
This Mechanical Engineering class page recommends adding a small 1 nF to 0.1 uF cap in parallel with small motors to reduce motor voltage spikes:
Would having both the protection diode and cap be counter-productive when PWM-controlling a 12VDC, 1-2A motor? Or would both be good?
Thanks,
Michael