The first page is no big deal if you can't handle this one solo the second will break you ;) , also i know it is tempting, but avoid using revolve to make those parts .
Page 2:
Start with modeling the the water path cavity as solid later you will substract it from rest of the body. your key sketch here is the section A-A , notice the profile is made out of arcs duplicate them in your sketch but fit a spline based on these sketched arcs that is your sweep path, the profile seems to be ø16mm circle, from here you can offset the faces and give it thickens and add rest of the features to create the main body. If you get stock share the file let us comment on it . As someone whom done few of these in my RL im will to guide you thru it, but i'm not going to make it for you.

Hello Dear Viknesh J
I designed your centrifugal pump today.
I hope it is useful for you.

That does look tough! This might help you - it's a 3D presentation detailing how a centrifuge works: https://link.jig.space/WLbfACPCFob

I can chat to the model's designer about how you could approach your design if you like? See if they have any tips...