The water pump, need check. As you know the sound it worst sympton for diagnosing. There are no other parts doing the metal attrition at right underneath.
You can call carman or another guy to check or directly send to garage ask them to listern.
会不会是排气管的问题
Could be possible.
Diagnosing by Listerning should be free.
Whoever can find out your problem based on what you described will be a genius and I shall raise my hat to him.
Send your car to a reliable garage. There is no free lunch in this country. Somehow somewhere you will have to pay this inspection fee... I have seen them all.