You have to know whether the tile inserts you’ve chosen are for wall or floor installation because the products that are produced for wall installations aren’t intended to bear a heavy load. They're lighter and a lot thinner compared to floor tile inserts. This means they’re not capable of resisting abrasive forces caused by foot traffic. So, remember that wall inserts are to be used on your walls ONLY.
As for floor metal tile inserts, they’re suitable for both your flooring and walls. They're now being used by interior designers and homeowners in giving accents to bathroom walls, especially if the tiles installed are large, rectangular ones. Although they are 20% heavier compared to wall tiles, most walls of homes can carry their weight. However, it is better to err on the safe side and check whether your walls are durable and sturdy enough to offer support for their weight.