Without friction would water flow or any liquid like blood through veins and arteries? I'm not including the surface that the water is flowing on just the water molecules.

 

Hope that makes sense.

Yes. An "Euler" fluid is an extrapolation to a perfectly inviscid fluid, and can serve as a useful approximation in some circumstances. Nevertheless, an invisicid fluid still responds to pressure differences, so imposing a pressure difference can still cause a fluid to flow.