Well, replacing it will not stop the buzzing. Waste of money? No probably not. If yours is original or it is not known how old it is, then it will more than likely give out. Maybe buy one & stick it in your glove box for peace of mind.
Yes I am a little daunted at the thought of replacing the intank pump! That is one reason why it is going to be done whilst I have 'back-up' in the shape of Cumbrianmale