I've seen that there is an option on android thtat allows to share 3g via usb.
is there a way to share Wi-Fi from a smartphone (XT1032)to another device via USB (the other device doesn't have a wi-fi receptor)?
The "3g tethering" shares whatever Internet connection you're using over USB. So, if you're connected to wifi, tethering will share the wifi connection over USB.
If the wifi disconnects the phone will automatically switch to sharing the 3g connection over USB.
For example, if you connect your phone over wifi, than connect your phone to your PC over USB and turn on tethering, your PC will have access to the Internet.
This might require installing some drivers though, which has your PC will automatically look for... on the Internet, which it cannot reach. So I suggest you install all drivers from the CD that probably came with your phone, or download the drivers on your phone and then install by sharing the phone storage with your PC.
I've used this method myself a couple of times when I was visiting someone with an old (802.11b) wifi receiver and a more recent (802.11n) access point to speed up the wifi (my phone has a better wifi chip).