If the motors are REALLY overheating, nothing can save them
Electrical motors don't like spinning slowly. We just melted a drill motor yesterday. Some advice - never allow a motor to sit there with some power applied to it
This happened to us when the default robot code was uploaded into the RC and an uncalibrated joystick was left connected to the OI for aout 2 minutes. So, either recalibrate speed controllers or create a large "deadzone" in your code.