Metal tiles are often used as accent pieces within tile floors or walls made from. Listellos (pictured on the right) and narrow liners (pictured on the left) are two common metal accents. The above metal tiles are from Paloma Pewter and come pre-sealed, so they can be inserted into shower installations and stand up to any corrosion water exposure might cause.
You can also consider using metallic resin-based tiles in the shower. These tiles mix metal with a resin, providing a metallic appearance within a resin coating. The resin coating helps keep the metal from corroding.
Tip: Pure metal tiles will be much heavier than resin-based ones. Also, beware of cheap metal tiles that can consist of a clay base with metal shavings just on the surface.