I recently installed a lower priced Shurflo pump and was very impressed with how little noise it made compared to the defective Aqua jet I took out.
Mind you, the Aquajet had rigid piping on the intake side and a length of flex hose on the outlet. When I put in the new pump I put a length of flex hose on both inlet and outlet.
The Surflow that I used had some sort of flexible mounting base to minimize sound transmission - I would have thought they would all have that, or rubber grommets or something. If not, you could improvise.
I can barely hear mine when it runs. The old one sounded as you describe - so maybe it was the hard piping on the inlet that caused the noise in my case.
I didn't change the old pump due to noise - it seized up.
Brian & Connie Mitchell
2005 Classic 30'
Hensley Arrow / Centramatics
2008 GMC Sierra SLT 2500HD,4x4,Crew Cab, Diesel, Leer cap.