Well whether with displacement or just bump mapping it’s going to take a more complex bump map to approach the effect, as you can see all that black dots get you are small holes, you need gradients around them to create the effect of the panel being punched-in.
Here are the settings I used for my test one, I just used a displacement map because I usally do when i get a Black and White image like that. There is a way of doing it with bump i believe but i cant remember it offhand