A jammed or clogged sump or sewage pump will eventually heat up internally and the motor will shut itself down. There is a thermal overload switch inside the pump that will automatically sense that the pump has cooled down and eventually the pump will try to run and pump again.
The thermal overload switch will protect the pump motor from overheating and burning out the electrical windings of the motor.
There is a limit to how long the thermal overload will last, we have been told by various motor manufacturers that this heat sensitive switch will last up to 20 days of heating up and cooling down.
In most cases, within a 20 day period the property owner or someone will notice that the pump is not running and will have it removed and checked. Beyond that 20 day time frame the motor could be permanently damaged and a dead short in the windings will cause the circuit breaker to fail. By that time the pump would have to be repaired or replaced.
Depending on the critical nature of the sump or sewage pump, a high water alarm would warn the property owner that this pump is not working and steps could be taken long before the pump is damaged or a flood occurs.