You run out of water!
The first thing that will happen is that the steering will become increasingly harder to use. And if not repaired this could lead to engine problems as well.
Running a pump dry will not damage the motor bearings at all. It is the pump seal that gets damaged. Some of the more modern pumps have enough water in them to allow the pump to run dry for quite a long time before seal damage occurs. It is the heat build up from the friction on the seal that causes failure. If you have run your pump dry and see any leakage at all, replace the seal immediately. The leaking water may "crawl" up the motor shaft and that is what will damage the motor bearings.
The engine will not run.
if you pump out too much water too fastdrought
It will over heat and seize. The liquids that a centrifugal pump move also act as the lubricant and cooling system for the pump. http:/enzperiodzwikipediazperiodzorg/wiki/Centrifugal_pump
Sounds like you may have burned out the fuel pump, they do not like to run dry.
If your well pump has a option for a water level sensor then you can add it your pump but more then likely you will have to buy a well pump that already has one in it.
If you have a submersible pump, and you run it dry long enough, the heat generated will melt the impellers and eventually destroy the motor. All this can happen in less than an hour. bob...
The flow will be restricted and you will have to run the pump longer and this will shorten the life of the pump. Above 50PSI you run the risk of causing the case of the filter to explode. Hatawa
The pump will be ruined and need to be replaced if the car was driven with a dry pump.
either the drive belt broke or the pump burned up from being run dry.
The hole in the pipe is to break an air lock that the pump may develop if the sump ever runs dry or the water level drops below the intake of the pump. Air inside the pump might not be purged out when the water level rises and the pump is called to turn on, causing the pump impeller to 'run dry' inside the pump. The hole allows the air to escape and the pump to prime itself and operate without an air lock condition.