Rust Dust....Whats grinding?

[shootin' for 500k]

Before I bought this the previous owner had the passenger side ball joints and axle replaced due to a ball joint failure. From what I know the driver side is original maybe?

I am hearing something like a grinding noise, that is smooth, very little vibration goes with it. I am thinking that it is coming from the passenger side front. After it rains, it is louder and after driving settles down some.

Can you guys tell me why this area has rust dust on it and where the white grease came from? I wiped alot of it off.

Driver side

 

[techno]

Inside the rubber boots is grease to lube the cv joint parts. The grease you can see can only have come from the previous axle when either the boot failed or when the ball joint joint failed the cv was most likely destroyed and spat grease everywhere. Double check the boots for rips or tears.
The rusty axle is probably an aftermarket part, not OE. Aftermarket stuff is rarely of the same quality, especially in corrosion resistance.