fastboot erase boot fastboot erase cache fastboot erase recovery fastboot erase system
fastboot flash bootloader "name of bootloader" fastboot reboot-bootloader
fastboot flash radio "name of radio" fastboot reboot-bootloader
fastboot -w update "name of zip file" or fastboot flash system system.img fastboot flash boot boot.img fastboot flash recovery recovery.img fastboot flash cache cache.img
fastboot erase userdata fastboot flash userdata userdata.img
fastboot reboot
References
http://androidforums.com/threads/guide-how-to-flash-a-nexus-factory-image-manually.706533/