Wish you could make it clearer and explain what "steel cactus" is for those who don't know. (We can't see the whole end of yard in one picture or two that we can put together?) Do you have any goals that include screening what's outside of the yard, or for creating more privacy?

you could put a simple screen in the corner to hide the pumps. the "Improvements" catalog has some nice screens. You certainly need some plants to screen them, and in those planting areas. You could also paint your "boring wall" to add some color and interest.

You say you have planted many things without success. What things? Are you planting native and adapted plants, or are you trying to plant east coast things which don't do well in the climate. What do you think is causing your failures? Not a good watering system? Is there caliche under there? what? You might ask for some plant recommendations here in the Arizona Gardening forum.

YV, I think "steel cactus" is . . . exactly that. Garden art made of
steel in the shape of a cactus -- saguaro I presume. Lots of steel
garden art in the desert.