Asked my husband this question, and his solution is to have the wrought iron powder coated. Its not cheap, and needs to be protected very good during shipping. If it gets a knick in it, you'll need to fix it right away so it won't rust.
We bought our place with wood furniture in it, and the wood ants (I call them termites) ate the chairs until they fell apart. I had to throw them away.
Kathy W.