Engine shuts off in low speed and at stop. I am told the water pump failed!!

If the water pump failed, your engine will overheat. Is it overheating? As for the issue with stopping at low speeds, your engine is equipped with a Mass Airflow Sensor. It will be located in the tube from the air filter to the throttle body. As a quick test, you can unplug the electrical connector to it with the engine not running. Start it up and see if your problem is fixed. If so, replace the MAF sensor. They run $50-80 on rockauto.com