pvrenderserver_mpich: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/lib64/mpich/bin/pvrenderserver_mpich - from package: paraview-mpich

You may install the required package with command yum install {package}
Error in other languages:
pvrenderserver_mpich: bevel nie gevind nie
pvrenderserver_mpich: comandă negăsită
pvrenderserver_mpich: comando não encontrado
pvrenderserver_mpich: commande introuvable
pvrenderserver_mpich: command not found
pvrenderserver_mpich: käsku ei ole
pvrenderserver_mpich: không tìm thấy lệnh
pvrenderserver_mpich: komanda nerasta
pvrenderserver_mpich: Kommando nicht gefunden.
pvrenderserver_mpich: kommandot finns inte
pvrenderserver_mpich: komut yok
pvrenderserver_mpich: nie znaleziono polecenia
pvrenderserver_mpich: níor aimsíodh an t-ordú
pvrenderserver_mpich: no se encontró la orden
pvrenderserver_mpich: no s'ha trobat l'ordre
pvrenderserver_mpich: opdracht niet gevonden
pvrenderserver_mpich: parancs nem található
pvrenderserver_mpich: perintah tidak ditemukan
pvrenderserver_mpich: príkaz nenájdený
pvrenderserver_mpich: příkaz nenalezen
pvrenderserver_mpich: команда не найдена
pvrenderserver_mpich: командата не е открита
pvrenderserver_mpich: 命令找不到
pvrenderserver_mpich: コマンドが見つかりません