For multi piece rims you will need to take a heck of a lot more time to clean them. Invest in air cans. Look at this website for products that will help you remove the water spots and help to "seal" the metal against brake dust.
Chrome polish, aluminum polish, stainless steel polish, metal sealant, Wolfgang metal polishes, Wenol metal polishes, Rolite metal polish, Flitz metal
You might need to invest in a power ball type polisher to generate the heat and RPM's needed to help remove really stubborn water spots.
Also make sure that there is no clear coat on your rims before you use some of these polishes. It will "rip off" the coating.
I have used Wenol on my HRE rims and that did seem to work well.