Spinning Wheels by Eve Langlais

Best friends Zak and Ray have only one goal in life: Upgrade their bodies until they’re more metal than flesh.
But to do that, they need to find more gears. And who better to help them find lost treasure than a seer who can predict the future and decipher the past?
Funny how she didn’t predict her own kidnapping.
Nema isn’t impressed with her supposed rescue by the Siyborghs. Part male. Part metal. She doesn’t approve of the parasitic cogs in their bodies. Especially since they pose a danger.
That doesn’t stop her from desiring them.
Even more tantalizing, they both want her, too.