A method of coating the inner surfaces of gas passages of a gas delivery system for a plasma process system such as a plasma etching system includes (a) flowing a fluidic precursor of a corrosion-resistant material through the gas passages and depositing a layer of the fluidic precursor to completely coat the inner surfaces of the gas passages; (b) removing excess fluidic precursor from the inner surfaces; (c) curing the deposited layer of the fluidic precursor to form a corrosion-resistant material coating.