As you are rooted: Wireless network data are stored in data/misc/wifi/wpa_supplicant.conf
-- so you could basically copy all its network
entries from one device and insert them on the other. The entries look like
network={ ssid="Telekom" key_mgmt=NONE priority=42 }
An easier way would be using the App Wlan Backup & Recovery (root): Backup all entries on one device, and restore them on the other. As you can see in below screenshot, the tool can even send the backup by mail -- so transfer to the other device should be easy:

But reading the comments on this app suggests it does not always work as expected: Users even recommend to use the manual way I described above.
Another option is using Titanium Backup, and restore the Wifi data on the other device. I did that successfully a couple of times, also cross-device and cross-ROM.
Third option is offered by the app Wifi Passwords (about USD 1), which allows you to share networks.