To get the all the wwn of the host in cluster use the below simple script.
#Input Cluster
$cluster = Read-Host "Enter Cluster name"
#will fetch the list of host in the cluster
$esxi = get-cluster -name $cluster | get-vmhost
#will get the wwn of host in the cluster,
Get-VMHostHba -VMHost $esxi| Select VMHost,Device,@{N="WWN";E={"{0:X}" -f $_.PortWorldWideName}}
copy this to a notepad and Save this as script_wwn.ps1 to any location and point to the location from vmware powercli console and run the script , as follows.
it will ask for cluster name, enter the cluster name and output will be as follows;
VMHost Device WWN
------ ------ ---
ESX01 vmhba0 218000E08B000186
ESX01 vmhba1 218100E08B200186