What type of glue will work well on wood and metal?
2-part epoxy is my usual recommendation when it comes to mating different kinds of materials together. That is usually one of the selling points. 

I would caution with the use of Gorilla Glue for this. While is might be a viable choice you need to be careful of its expansion properties. If you do try to use it make sure you clamp appropriately and clean any excess that seeps out. That is general advice for gluing in general but you really don't want warping in the final product here. 

Depending on the size of the veneer and how it is prepared there is a chance for small pockets to exist where the glue could expand. As long as you clamp firmly for the duration of the setting time you should be fine though.