you have to install them through the bootloader in fastboot mode. Then you can flash each image of the stock images to their respective partitions.
For example, to flash the system.img, you would type into the console for fastboot
"fastboot flash system system.img"
However, I don't have any experience with the moto g and I know they have some different partitions and some weird files included so you might want to look up a guide on how to go fully stock
Here's one I found.
http://forum.xda-developers.com/showthread.php?t=2542219
for fastboot and adb as well (dump all the stock images into the installation folder of this application and run it by just using the start menu link)
http://forum.xda-developers.com/showthread.php?t=2317790