There's no reason to replace that rusting lamp post. Simply remove the rust and apply some new paint instead.
Step 1 - Prep the Surface
Always remove loose, flaking paint, dirt and grime with steel wool and wire brush.
Step 2 - Grind Deeper
Use the high speed rotary tool and #500 aluminum oxide grinding wheel or #530 stainless steel brush to remove hard to reach rust.
Step 3 - Inhibit Rust
Rust forms quickly, so immediately apply a rust inhibitor to all bare surfaces and joints.
Step 4 - Paint
Use two coats of oil based or metallic paint to finish up.
Courtesy of Dremel Tools